package org.codehaus.mojo.properties;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

class CircularDefinitionPreventer {
    private static class VisitedProperty {
        private final String key;

        private final String value;

        private VisitedProperty(String key, String value) {
            this.key = key;
            this.value = value;
        }
    }

    private final List<VisitedProperty> entriesVisited = new LinkedList<>();

    // boolean value denoted whether or not the property is deemed "resolvable"
    private final Map<String, Boolean> keysUsed = new HashMap<>();

    /**
     * @param key The key.
     * @param value The values.
     * @return {@link CircularDefinitionPreventer}
     */
    public CircularDefinitionPreventer visited(String key, String value) {
        entriesVisited.add(new VisitedProperty(key, value));

        if (value != null && isValueResolved(value)) {
            keysUsed.replaceAll((k, resolvable) -> true);
        } else if (keysUsed.containsKey(key) && Boolean.FALSE.equals(keysUsed.get(key))) {
            circularDefinition();
        }
        keysUsed.putIfAbsent(key, false);

        return this;
    }

    private void circularDefinition() {
        StringBuilder buffer = new StringBuilder("Circular property definition: ");
        for (Iterator<?> iterator = entriesVisited.iterator(); iterator.hasNext(); ) {
            VisitedProperty visited = (VisitedProperty) iterator.next();
            buffer.append(visited.key).append("=").append(visited.value);
            if (iterator.hasNext()) {
                buffer.append(" -> ");
            }
        }
        throw new IllegalArgumentException(buffer.toString());
    }

    private boolean isValueResolved(String value) {
        int prefixPos = value.indexOf("${");
        int suffixPos = value.indexOf("}");
        return !(prefixPos >= 0 && suffixPos > prefixPos);
    }
}
